The sequencing using state-of-the-art technology identified not only all the immune gene families and their functions, but provided insights into how the retrovirus has colonised the animal’s DNA.

“For the first time we’ve been able to see how many times a virus is inside a single animal,” Professor Timms said.

“And it’s not all equal, there are different strains in there.”

He said the level of detail will enable them to identify which strains are more dangerous so they can tweak tests and vaccines to target the virus.

“We couldn’t do that before because we didn’t know what to look for.”

The genome will help Professor Timms and his team monitor how different animals respond to vaccines.

“Now we’ve got that information and we can start doing proper genetic studies on the animals,” he said.

The legacy of Pacific Chocolate, Bilbo and Birke

The project, which took five years to complete, is based on samples taken from three koalas: Pacific Chocolate and Bilbo, two female koalas who succumbed to chlamydia; and a male called Birke, who was mauled by a dog.

“Those are pretty emotive moments where you sit and watch an animal being necropsied (examined after death),” Professor Johnson said.

“It reminds you about why we’re doing what we’re doing.”

The genetic information from the koalas, which were from northern New South Wales and southern Queensland, provided insights into the diversity of populations right around Australia.

“We found relatively high levels of genetic diversity in the Queensland and New South Wales population and much less diversity in Victorian and South Australian population,” Professor Johnson said.